LIFE'S RATCHET

How Molecular Machines Extract Order from Chaos

A biophysicist examines the relationship between chance and necessity at the boundary between life and inanimate objects.

Hoffmann (Physics and Materials Science/Wayne State Univ.) founded his university's Biomedical Physics program in order to apply the latest advances in nanotechnology to probe the nature of life. Although his field of expertise is physics (he admits to having never formally studied biology), while still in graduate school, he became fascinated by the discrepancy between life at the level of atoms and molecules, where “chaos reigns,” and at the larger scale of human existence, where, for the most part, “order prevails.” With the development of the atomic force microscope, which can sense motion, scientists are now able to witness the action in living cells of molecular machines, “autonomously moving molecules performing specific tasks like tiny robots.” The author applies Darwin's profound insight into the evolution of species to the question of how life itself evolved. He shows how Darwin implicitly resolved the split between reductionism and vitalism with the discovery of natural selection. Hoffmann distinguishes between macroscopic machines created to serve a specific purpose and the “autonomous [molecular] machines” found in life. He believes that the key to their functioning is the relationship between different kinds of energy at the nanoscale level, where different kinds of energy (chemical, electrostatic, thermal, etc.) operate on the same scale. He speculates about the “exciting possibility that the molecules in our body can spontaneously convert different types of energy into one another.” By creating order from the chaotic storm of thermal energy through a process of natural selection, the mechanisms and enzymes necessary for a cell to live come into being. “Evolution is not random,” Hoffmann writes. “It is a collaboration between a random process (mutation) and a nonrandom, necessary process (selection)...all of nature is a result of this balance.”

A fascinating mix of cutting-edge science with philosophy and theology.